One vertex per element, one color per generator, with an edge from x to x·s.
(2,5)(3,6)(7,8)(9,10,14,18)(11,16,20,24)(12,17,13,15)(19,22,21,23)(26,30)(28,35)(31,39)(32,36)(34,37)(38,40)(1,2,4,5)(3,6,7,8)(10,15)(12,13)(16,22)(17,18)(19,21)(23,24)(25,26,29,32)(27,31,33,40)(28,36,35,30)(34,38,37,39)(1,3)(2,6)(4,7)(5,8)(9,11)(10,16)(12,21)(13,19)(14,20)(15,22)(17,23)(18,24)(25,27)(26,31)(28,37)(29,33)(30,38)(32,40)(34,35)(36,39) involution — undirected(9,12,14,13)(10,15,18,17)(11,19,20,21)(16,23,24,22)(27,33)(31,40)(34,37)(38,39)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.